Lifting magnets



Oct. 22, 1957 H. E. HDGsoN LIFTING, MAGNETS Filed Oct. 9. 1953 UnitedStates Patent LIFTING MAGNETS lHoward E. Hodgson, Wauwatosa, Wis.,assigner to Cutler- Hammer, Inc., Milwaukee, Wis., a corporation ofDelaware This invention relates to improvements in lifting-magnets andmethods of making the same. More specifically, it relates to means forinterlocking the magnet winding and the magnet core, and to methods ofmaking an electromagnet employing such interlock means.

Heretofore, a source of trouble frequently encountered in the use oflifting-magnets has been excessive movement between the magnet core andthe magnet winding. Such movement has often resulted in broken orshorted leads, thus incapacitating the magnet until the necessaryrepairs could be made.

Such undesirable movement between the magnet winding and core usuallyoccurs in electromagnets which are subjected to frequent rotativemovement during normal use. Such is the case with lifting-magnets whichare -subjected to many torsional shocks and strains in the course of adays work.

The primary object of this invention is to provide a lifting-magnetwhich will readily withstand the shocks and strains to which it isnormally subjected.

Another object is to provide a method of winding a lifting-magnet; whichmethod provides interlocking the magnet winding with the magnet core toprevent relative rotational movement therebetween.

Another object is to provide simple and inexpensive means for positivelyretaining the magnet winding in a given position with respect to thefixed magnet parts.

Another object is to provide an eflicient lifting-magnet which willwithstand severe service and' obviate the necessity for constant repair.

Other objects and advantages of the invention will become apparent fromthe following description of a specie embodiment when read in connectionwith the accompanying drawings, in which:

Figure l is a fragmentary view of the core and winding of alifting-magnet embodying my invention;

Fig. 2 is a fragmentary sectional view, taken along the line 2-2 of Fig.1, and

Fig. 3 is a fragmentary sectional view, taken along the line 3-3 of Fig.1.

Like reference characters indicate corresponding parts throughout theseveral views of the drawings.

Referring to the drawings, they show a magnet core having a outerperiphery 10a. Attached to said outer periphery 10a of core 10 is a pairof keys 12 each of which is held in place by several studs 14press-fitted into engagement with recesses 10b in core 10. As shown inFig. 1, keys 12 are circumferentially spaced a suitable distance fromeach other on periphery 10B.

After fastening of said keys 12 to core 10, several complete turns ofinsulating sheet material such as mica are wound on the outer peripheryof core 10. Although not essential to successful operation of thepresent invention, I prefer to use only a portion of a complete turn ofinsulating material against the core. Thus insulating strip 16 extendsfrom the outer side of one of the pair of keys 12 to the outer side ofthe other one of said keys.

Between said keys 12, and having its intermediate portion restingagainst said outer periphery 10a, is a small strip 16a of insulatingmaterial which bridges and overlaps said keys as shown in Fig. l. Woundaround said strips 16 and 16a are one or more complete turns 16b ofinsulating material. Although not necessary to successful operation ofthis invention, I prefer to subject insulating strips 16 and 16a andturns 16b to a reasonable amount of heat to thereby improve theformability thereof while being positioned shown in Fig. l. Such stripsand turns are thus caused to follow very closely the irregularitiescreated by keys 12.

Wound around said complete turns 16b of insulating material are asuitable number of complete turns 18 of magnet winding materialcomprising copper strips 18a and any suitable insulating material suchas asbestos paper 18h. As shown in Fig. 1, I prefer to wind one of thecopper strips 18a against the complete turns 16b of insulating materialand thereafter continuing the winding of copper strips 1821L togetherwith asbestos paper 18b so that each complete turn of copper strip isinsulated from adjacent turns of copper strip by the asbestos paper.

An insulating spacer block 20 is then positioned against the severalcomplete turns of magnet winding material between keys 12 as shown inFig. 1. That is, block 20 is circumferentially positioned with respectto core 10 so that said block 28 is intermediate the keys 12. Block 2t?is forced against said magnet windings 18 by any suitable method to thusincrease the interlocking of keys 12 with the entire winding.

A suitable number of insulating strips 22 are then positioned againstthe several complete turns 18 of magnet winding material as shown inFig. l to thus effect the desired contour of the magnet winding and toassist in preventing the 'undesirable slippage.

Following positioning of block 20 and insulating strips 22, completeturns 24 of magnet winding material necessary to provide the desirednumber of ampere turns are then tightly Wound on the core. Said completeturns 24 press insulating block 20 against the several complete turns 18of magnet winding material, thus causing the small insulating strip 1Gbto bind against keys 12. Such binding action thus prevents anysubstantial degree of relative movement between the completed magnetWinding and the magnet core.

As shown in Figs. 2 and 3, it is often desirable to use several completemagnet windings on the same magnet core. In this event, each of themagnet windings is insulated from adjacent windings by insulating discs26. If the electrical potential difference between adjacent windings isquite large due to the manner in which the windings are connected, Ithen prefer to employ insulating strips 28, each of which is of L-shapein cross section as shown in Figs. 2 and 3. Insulating strips 30 areemployed in size and number in accordance with the electrical potentialsto be encountered.

Although I use keys 12 which extend across the several magnet windingsused (Fig. 2), I prefer to employ individual insulating spacer blocks 20for each winding because of the variation in size of the insulating andmagnet winding materials and to permit the use of discs 26 forcompletely insulating adjacent windings from each other.

Although I have shown and described `a specific embodiment of myinvention, I am fully aware that many modifications thereof arepossible. My invention, therefore, is not to be restricted except in sofar as is necessitated by the prior art.

I claim:

l. For use in an electromagnet, in combination, a magnet core, a pair ofkeys spaced from each other on said magnet core, a plurality of turns ofmagnet winding on said core and over said keys, and a spacer positionedbetween said keys and pressed inwardly of said core between adjacentturn layers of .said pluralityof turns of said magnet winding tointerlock` underlying. layers of turns with said keys to restrain saidmagnet winding against slippage on said magnet core.

2. For use in an electromagnet, in combination, a magnet core having aperipheral surface, a, pair of keys positioned on said peripheralsurface and providing a space therebetween, a plurality of turns ofmagnet winding on said core and over said keys, and a spacer positionedat least partly within said space between said keys and being pressedinwardly of said core between adjacent turn layers of said plurality ofturns of magnet winding to interlock underlying turn layers, to saidkeys to prevent substantial relative movement between said mag netwinding and said magnet core.

3. For use in an electromagnet, in combination, a cylindrically shapedmagnet core, a pair of keys circumferentially positioned from each otheron said core, a plurality of turns of magnet winding on said magnet coreand said keys, and a spacer circumferentially positioned between saidkeys with respect to said magnet core, said spacer being pressedinwardly of said core between adjacent layers of turns of said pluralityof turns to press underlying layers of turns into interlockingengagement with said keys to thereby prevent relative movement betweensaid magnet winding and said core.

4. For use in an electromagnet, in combination, a cylindrically shapedmagnet core, a pair of keys circumferentially spaced from each other onsaid magnet core, at least one complete turn of insulating winding on`said magnet core and over said keys, at least one complete turn ofmagnet winding on said insulating winding, an insulating spacer pressedinwardly on said magnet winding between said keys, insulating filleralso on said aforementioned magnet winding to provide the desiredcontour, and additional turns of magnet winding on said insulatingspacer and ller providing the desired total Winding turns and holdingsaid spacer pressed as aforedescribed to interlock the magnet windingwith said keys to prevent relative movement therebetween.

5. For use in an electromagnet, in combination, a cylindrically shapedmagnet core, a pair of keys circumferentially spaced from each other onsaid core, each of said keys having an edge parallel to the axis of saidcylindrically shaped core, a plurality of turns of magnet winding onsaid' magnet core and said keys, and a spacer circumferentiallypositioned between said keys and lying between adjacent turn layers ofsaid plurality of turns and held pressed inwardly toward said core byoverlying turn layers to interlock underlying turn layers with saidedges of said keys to prevent relative movement between said magnetwinding` and said core.

6. For use in an electromagnet, in combination, a cylindrically shapedmagnet core, a pair of keys circurnterentially positioned from eachother on said magnet core, each of said keys having an edge parallel tothe axis `of said cylindrically shaped core, at least one complete turnof insulating Winding on said magnet core and over said keys, at leastone complete turn of magnet Winding on said insulating winding, aninsulating spacer on said aforementioned magnet windingcircumferentially located between said keys, insulating ller also onsaid aforementioned magnet winding to provide the desired contour, andadditional turns of magnet winding on said insulating spacer and fillerto provide the desired nurnber of total winding turns, said additionalturns pressing said spacer inwardly toward said magnet core to interlockunderlying layers of the magnet winding with said edges on said keys toprevent relative movement therebetween.

7. For use in an electromagnet, .in combination, a magnet core providedwith Vmeans comprising spaced apart opposing shoulders, a plurality ofmagnet Winding turns on said core over said shoulders, and a spacerpositioned between sai'dshoulders and pressed inwardly of Ysaid corebetweenadjacent turn layers of said winding to inter- *lockVunderlying'layers of said turns with said keys to restrain said magnetwinding against slippage on said magnet core.

yReferences Cited in the le of this patent UNITED STATES PATENTS1,325,914 Rowell Dec. 23, 1,919

2,391,229 DEntremont Dec. 18, 1945 2,476,049 Leitch July 12, 19492,544,845 Link Mar. 13, 1951 2,583,124 Sampietro `lan. 22, 1952 FOREIGNPATENTS 564,110 Great Britain Sept. 13, 19.44

